Slick oil: Richard Wilson's 20:50 at the Saatchi Gallery

12 January 2010: You may have seen artist Richard Wilson's oleaginous installation before. Created over 20 years ago, this spectacular waist-high reservoir of recycled sump oil, one of Britart's most iconic installations, was bought by collector Charles Saatchi and has been exhibited at his various galleries in London – first at Boundary Road in St John's Wood, then at County Hall beside the Thames.

Wilson has become renowned for his site-specific installations. Of this work he says: 'It can be applied to any internal space ... and in each space it will be radically different – because it will reflect it and adapt to its parameters'